1. Field of the Invention
This invention relates to the field of data processing. More particularly, this invention relates to trace operations in data processing systems, such as are used during de-bugging of software and development of hardware.
2. Description of the Prior Art
An important function in providing trace operation is to provide trace data giving the address of the instruction currently being executed by the data processing system. If this trace information is to be provided in real time, then a dedicated bus is used to provide this trace address information to an external analysis system.
A problem with the above-mentioned approach arises due to the increasing bit lengths of addresses used within data processing systems, i.e. it is increasingly common to use 32-bit address, which would require a trace bus of at least 32-bits to carry the trace addresses in real time. It will be appreciated that the need to provide such large trace buses is a significant disadvantage. The number of external connection pins of an integrated circuit that would be required to carry out this trace bus would be a significant proportion of the total number of connection pins and results in an increase in the cost of the integrated circuit and/or limitations on the connection pins that may be provided for other purposes.